This invention relates to a sheet feeding apparatus of the friction retard type. An advanceable retard member is arranged in a nipped configuration with a feed member with the sheets passing therebetween. In accordance with this invention, an apparatus is provided for incrementally advancing the retard member in response to the operation of a drive system associated with a sheet stack elevating mechanism.
A wide variety of friction retard type sheet feeding and separating apparatuses are known in the art. U.S. Pat. Nos. 3,035,834 to Bottrell; 3,198,514, to Barbera et al.; 3,260,520 to Sugden; and 3,635,465 to Beery are exemplary of a large number of patents disclosing moving belt type retard members which are moved in either the sheet feeding direction or counter thereto. U.S. Pat. Nos. 2,892,629 to Osgood et al. and 1,955,066 to Hiller are exemplary of patents disclosing the use of moving retard rolls in a friction retard separator.
U.S. Pat. No. 3,768,803 to Stange is particularly relevant insofar as it describes, particularly by reference to FIG. 16 thereof, the use of a belt type retard member which may be either continuously or incrementally advanced. The retard belt is arranged in association with a feed belt and deformably engages the feed belt in an unsupported section to form a nip for sheet advancement therebetween.
It has been found desirable in accordance with the present invention to provide an apparatus for incrementing a retard member such as a web, belt or roll, which conserves power, which is low cost and which provides improved wearing of the friction surface of the member. It has further been found desirable to preferably provide non-uniform incrementation of the retard member which should further improve the wearing of the friction retard surface.